Ascension Health review: Billing

I made the required payment through a collection agency they sent a $50 dollar account overdue balance. I paid the company Frost (the collection agency) they use, and they are not acknowledging this payment made to a collection agency that they themselves referred me to. I am now receiving bills for the same service and amount owed that has already been paid for. I called billing multiple times and I was informed they will contact their collection agency used Frost and update my account. It was never done and they are billing double.